Nothing.

I stopped right at the point where I'd get strongly diminishing returns. Sure, I could have purchased a 280x instead of the 270, but for what purpose? So I can play TF2 at 300 fps instead of 200? =P

The only demanding games I've played in the past year are Bioshock Infinite (high, 60 fps), Alan Wake (medium, 60 fps), and Sanctum 2 (medium-high, 60 fps).

It suits my needs perfectly, and I have no regrets =)

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